This invention relates to coil-type dialyzers or membrane diffusion devices of the type used in artificial kidney systems; and more particularly, to an embossed membrane support member for use in such devices.
Coil dialyzers used in artifical kidney systems, such as the one disclosed in U.S. Pat. No. 3,743,098, include an elongated tubularly-shaped semipermeable membrane and a membrane support member which are wound together about a cylindrical core. Blood from a patient flows through the dialyzer inside the membrane and dialysis solution flows though the dialyzer in a crosswise direction. The dialysis solution flows between the windings of the membrane and support member so as to contact the membrane and receive bodily waste products from the blood.
The membrane support disclosed in U.S. Pat. No. 3,743,098 is a foraminous screen. Recently, embossed support members have been developed which include an imperforate center who having equal-height support ribs on each side of the web. The ribs engage and position the membrane in the dialyzer, as well as define flow channels between the support member and membrane for the dialysis solution.
The membrane is made from cellophane or cellulose derivative, such as sold under the trade name Cuprophan. Such materials stretch approximately three times as much in the transverse direction as in the longitudinal direction. It is believed that, when the embossed, imperforate support members are used, portions of the membrane may stretch or droop and thus contact the web between the ribs. Such contacting could block the flow channels or otherwise adversely affect the flow of dialysis solution between the web and membrane and thereby reduce the effectiveness of the dialyzer.
It is therefore an object of this invention to provide an embossed support member which is constructed to prevent the membrane from contacting the web so as to assure uniform dialysis solution flow and contact with the membrane.
The foregoing and other objects and advantages will be apparent from the following description and appended claims taken in conjunction with the accompanying drawings.